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Don't appreciate telemarketer calls on house phone or cell phones.
Can they be stopped?

You can request  that they stop calling.  If they are in fact,  an actual legitimate Telemarketing company they will abide,  because if they are reported multiple times to the DNC  they can get a hefty fine.
             Telemarket=Telephone sales of taxable goods or services.

Legitimate Telemarketing companies are easily identified and located because they have actual business phone numbers,  physical addresses,  and pretty much must identify themselves in order to communicate with their customers.   (There is always going to be those who fudge a little.)

Most unwanted calls are not from actual Telemarketing companies. Many people refer to all unwanted calls as telemarketers.  Calls from actual legitimate Telemarketing companies to those on the DNC list are Rare.  Those that do,  usually have a loophole that allows them to legally call you,  until you tell them to stop.

If they are a scammer and crook  there isn't much you can do except report them and/or use a call blocker.
The thieves don't go by the law.     And of course,  the charities,  politicans,  surveys,  non-profit,  and more are exempt.

Another unwanted call.  three times within the last week

Short answer, unfortunately no.  Sorry to say.  Calling elderly.  Please protect your loved ones from these potential crooks.